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Title: Unity power factor active rectifier and DC bus controller
Author: Zhou, Zhongfu.
Awarding Body: University of Sussex
Current Institution: University of Sussex
Date of Award: 2003
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A Unity Power Factor Active Rectifier and DC Bus Control system is described in this thesis. The aim of an active rectifier controller is to draw sinusoidal input current with unity power factor, and to provide fast response to DC load disturbance, whilst maintaining the DC link voltage as constant as possible. To achieve this aim, a current control structure based on voltage vector modulation has been developed using both stationary and synchronous reference frames. To improve response speed and stability, reduce transient overshoot, and overcome the drawback caused by the inherent dead time delay in the digital control loop, a Smith Predictor is introduced into the control loop to compensate for the dead time delay. To speed up the response to DC link current disturbance, the control structure incorporates DC bus voltage feedback regulation plus DC link feed-forward current control. For mains supply synchronization, a software digital Phase Locked Loop (PLL) is used, designed for low sensitivity to supply voltage noise. To further improve performance, a double update pulse width modulation (PWM) mode is utilised. To implement feed-forward current control without the need for multiple DC link current sensors and associated communication channels in applications where the common DC bus system feeds multiple variable speed drives, a robust minimum order DC link current observer has been designed to provide the required feed-forward current signal. To investigate the performance of the active rectifier controller, a simulation program based on VissimTM has been developed and simulations carried out for both 20A and 500A step change load currents. An experimental system has been built using a ADMC401 digital signal processor as the control core, and experiments conducted using different control schemes. Both simulation and experimental results show the validity of the control model
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available